Max,

We worried about things like you talk about. Even more so when we departed the USA and went into a marina that had a sign that said that the dock water was NOT for drinking.

Most likely overkill for any one who is not long term cruising, but what we did is to ALWAYS use this water filter. We bought it in Mexico. It's 2 normal filers (10 micron and a 2 micron) and a UV sterilizing light. If water does not come out of our water make, it goes through this unit. That way I KNOW our water is good.

We also use a PUR filter on our drinking water even though we know our tank water is good.

Greg